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Environmental fate & pathways

Hydrolysis

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Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Principles of method if other than guideline:
Detailed data at pH 7.0, 7.8 and 8.4
GLP compliance:
no
Transformation products:
yes
% Recovery:
27.3
pH:
8.4
Temp.:
12 °C
Duration:
357 h
pH:
4
pH:
7
Temp.:
12 °C
DT50:
279 d
pH:
9
pH:
7.8
Temp.:
12 °C
DT50:
21 d
Details on results:
Total recovery derived from following IUCLID4 degradation at pH 8.4 and 12 °C: Degradation (in %): = 72.7 after 357hour(s)

The reaction of CHPTAC in neutral and alkaline pH does not
correctly fit into the definition of hydrolysis but the
reaction is more a conversion reaction.

As the degradation reaction is a reaction of CHPTAC with
OH-ions, the ln c/time plot is not linear and the pH was
decreasing with time. In order to approximate the rate
constants at the given pH values only those values of the ln
c/time plot were used that corresponded to the target
pH-values (pH +-0.1 target pH 7.8 and 8.4). 


pH    kobs [h E-1]  t1/2 [h]

7.0   1.0 x 10 E-4   6700
7.8   1.4 x 10 E-3    505
8.4   5.4 x 10 E-3    127

The major degradation product was EPTAC, minor amounts were
converted to DHPTAC.

Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
QUAS020
Radiolabelling:
no
Analytical monitoring:
yes
Transformation products:
not measured
pH:
4
Temp.:
25 °C
DT50:
> 1 yr
Remarks on result:
other: The results at 25 °C were calculated from the measured temperatures (50 and 35°C).
pH:
7
Temp.:
25 °C
DT50:
641 h
Remarks on result:
other: The results at 25 °C were calculated from the measured temperatures (50 and 35°C).
pH:
9
Temp.:
25 °C
DT50:
< 1 d
Remarks on result:
other: The results at 25 °C were calculated from the measured temperatures (50 and 35°C).

The results of the preliminary test showed that (3-chloro-2-hydroxypropyl)trimethylammonium chloride is stable at pH 4
(degradation < 10 % after 10 days). At pH 9 the abiotic degradation was > 50 % after 2.4 hours. The main test was only carried out at pH 7.

The results of the preliminary test verify that the hydrolysis reaction is directly influenced by the OH(-)
concentration. Therefore the kinetics of the abiotic degradation of (3-chloro-2-hydroxypropyl)trimethylammonium
chloride is refered to as base catalysed.

k(obs)-values and the corresponding half lifes from the main test at pH 7 and extrapolation to 25 °C:

Test  Temp.  pH 4  t(1/2)  pH7     t(1/2)  pH9   t(1/2)
-----------------------------------------------------------
 1    50 °C  -     -       0.117     6 h   -     -
 2    35 °C  -     -       0.008    90 h   -     -
 *    25 °C  -     > 1 yr  0.001   641 h   -     < 1 d

* extrapolated

The results at 25 °C were calculated from the measured temperatures (50 and 35°C).

Description of key information

The measured half-life of CHPTAC at pH 7.8 and 12 °C was 21 days.

Key value for chemical safety assessment

Half-life for hydrolysis:
21 d
at the temperature of:
12 °C

Additional information

The reaction of CHPTAC with water is more complex than a simple first order hydrolysis reaction. In a standard hydrolysis test conducted according to EC test method C.7 the half-life at 35 °C and pH 7 was 3.75 days. Extrapolating to environmental conditions (12 °C) the corresponding half life is predicted to be 75.5 days. However, other evidence suggested that true reaction rates under neutral conditions were faster than this, therefore a study was performed under environmentally relevant conditions (Raisio, 2004). In this study the measured half-life of CHPTAC at pH 7.8 and 12 °C was 21 days.